a. Field of the Invention
This invention relates to apparatus for treating tow with fluid.
B. Description of the Prior Art
In the manufacture of acrylic filaments by certain processes, it is necessary to anneal or heat treat the filaments and allow them to shrink in order to prevent subsequent filament fibrillation. The conventional method of annealing acrylic filaments is a batch process, where a tow of the filaments is placed in an autoclave and the autoclave filled with steam under pressure. A disavantage of this method is that it is a batch process. Also, excessive handling of the filaments is required.
Attempts have been made to anneal acrylic tows by continuous processes at steam pressures above atmospheric. In some of these attempts, tows were passed through a chamber containing steam under pressure and having seals at each end through which the tow is passed. These devices suffered from poor sealing and excessive wear of the seals.
Attempts have been made to anneal acrylic tow using steam at atmospheric pressure in a device having no seals. In these devices, steam penetration of the tow has been poor and frequently the tension necessary to pull the tow through the device has prevented adequate tow shrinkage. Unless the tow is allowed to shrink, the filaments will tend to fibrillate under conditions of usage.